OCLN and Menkes disease: However, protein levels of occludin (0.3944 ± 0.0378 vs. 0.9095 ± 0.0800, p < 0.001) and ZO-1 (0.4335 ± 0.0431 vs. 0.9426 ± 0.0532, p < 0.001) were markedly downregulated in MD group than MC group, while no significant change was observed in MG group.